Method and apparatus for stacking sheets of wood pulp and the like in bales of uniform weight



1960 E. B. BORTHEN ETAL 2, 58,433

METHOD AND APPARATUS FOR STACKING SHEETS 0F woon PULP AND THE LIKE IN BALES 0F UNIFORM WEIGHT 2 Sheets-Sheet 1 Filed March 12, 1957 m 5 m m E Hm m m fl A E Y B Z Lufi QAAN ATTORNEY- Nov. 1, 1960 E. B. BORTHEN ETAL Filed March 12, 1957 2 Sheets-Sheet 2 FIE-2- INVENTORY: .E'YYJND Efluzzgwmg,

BY CARL-ERIC Sausmzm krrakmgx.

tates METHOD AND APPARATUS FOR STACKING SHEETS F W001) PULP AND THE LIKE IN BALES OF UNIFORM WEIGHT Filed Mar. 12, 1957, Ser. No. 645,424

5 Claims. (Cl. 214-452) In a mill producing wood pulp, logs are cut and shredded mechanically and chemically into water borne fibrous particles and ultimately formed into a comparatively dry web of pulp. Near the delivery end of the pulp machine, when the pulp is to be shipped in bales, the web is sliced lengthwise into strips of equal width and then the strips are cut crosswise at fixed intervals to form uniformly dimensioned sheets. A quite common size of such sheets is thirty-six by twenty-four inches. The rows of sheets delivered by the machine are dropped upon a receiving platform in separate stacks or piles.

It has been the practice in the past for workmen to transfer the stacks individually to a weighing scale and by manually adding or removing sheets to bring the final stacks to approximately the desired bale weight which usually is a set figure of four or five hundred pounds, on the basis on which payment is made. Each stack is then wired or banded under compression into a bale for shipment.

In carrying out the above method the attendants wait until all the stacks reach a height roughly corresponding to that of a stack having the desired weight and then transfer such stacks by conveyor or truck to the weighing scale. This practice heavily concentrates the labor at spaced intervals leaving idle time between.

Under the pressure of handling a number of pulp stacks in quick succession the weighing is done hurriedly, with the workman transferring a handful of sheets at a time to bring the stack near the desired weight. To avoid creating any underweight bales the workman will almost invariably pile on extra sheets. Consequently, by giving more pulp than it is paid for, the producing mill will suifer at least a slight monetary loss, an average of one percent, on each bale. As the ordinary pulp plant may have an output of 250,000 bales per year, the annual loss can be the equivalent of 2,500 bales.

Another objectionable feature of the practice of taking such stacks of the height approximating the desired weight of the bale to be shipped arises from the fact that the percentage of Water in the pulp is generally greater toward the edges of the pulp web as it arrives from the pulp machine. At the same time the difference in the amount of water afiects very slightly, if at all, the thickness of the Web. Pulp usually handled in sheet form and shipped in bales has an overall moisture content of ten to fifteen percent. However, it may run as low as five percent at the center of the web and as high as twenty percent along the borders.

Accordingly, the sheets from the outside rows of the sliced web will be heavier due to their greater water content than those in the inner rows, while not being any thicker. Bales formed from the outside sheets do not require as many sheets to reach the desired weight and will be shorter than the bales built from the inner rows of sheets.

The principal object of this invention is to provide a method and apparatus for automatically forming stacks atent ice of sheets of wood pulp as close as possible to the exact weight desired in the final bale of pulp to be shipped.

More specifically it is an object of this invention to provide a method and apparatus which receives stacks of sheets at weights above the desired weight and automatically removes sheets from each stack until the desired weight is reached.

It is a further object of this invention to pile the sheets removed from the overweight stacks in additional stacks of the desired weight.

The method and apparatus of the invention bywhich these objects are attained may utilize a conveyor arrangement placed crosswise of the delivery end of the pulp machine to receive the several rows of sheets delivered by the machine. A conveyor of this type is shown in US. patent application Serial No. 610,919, filed September 20, 1956 by Karl Y. Sundblad.

The conveyor has stacking stations separated by raisable dividers to accommodate the number of rows of sheets delivered by the machine. In practising this invention, when the stacks on the conveyor have reached a height known tobe in excess of that of stacks of the desired weight, the conveyor moves them away from the pulp machine and transfers them to a separate conveyor.

The latter conveyor delivers the stacks individually at governed intervals to a position over a weighing scale. Adjacent the scale is mechanism for removing sheets one at a time from the stack until the desired weight is reached.

The removal of sheets is then interrupted and the stack is forwarded to a baling station for compressing and banding. The next overweight stack is then brought-in position over the scale and sheets are removed therefrom until the preselected weight is registered.

The surplus sheets from the overweight stacks are piled on another conveyor over a second scale and when the stack thus built up reaches the desired weight the stack is moved by the conveyor off of the scale for delivery to the baling station.

The objects and advantages of the invention will be more apparent upon reading the following description and referring to the drawings in which:

Figure 1 is a front elevation of the primary scale receiving the overweight stacks; the excess sheet transferring mechanism; and the secondary scale on which the stacks are formed with the surplus sheets; and

Figure 2 is a vertical section taken on the line 22.

of Figure 1.

Referring to the drawings in more detail, the conveyor 3 receives the overweight stacks from the conveyor that is positioned across the delivery end of the pulp machine. An overweight stack 5 has been delivered between guide plates 6 and 7 by conveyor 3 to the primary scale 9. The head 10 of the scale encloses the conventional weight indicating dial. A reporting device 12 extends over the face of the dial in line with the figure on the dial indicating the selected weight. photo cell or induction element responsive tothe arrival of the weight indicating pointer at the selected weight figure.

A motor 14 driving the conveyor 3 may be under the control of electronic equipment 15 responsive to the reporting device 12 to stop the conveyor with the arrival of an overweight stack at the scale station and the accompanyh 'g swinging of the indicating pointer past the device A carriage 16 mounted on rollers 17 and 18 is horizontally rec1procated by the action of air cylinder 20. Upon the arrival of a new stack on the primary scale 9 cylinder" The device 12 may be'a,

from the'forward end of carriage 16 is a series of suction cups 22.

The cups 22 are held in a raised position by their connection with a piston in air cylinder 24 until the carriage brings the cups immediately above the stack 5. Then release of the air from cylinder 24 permits the suction cups to descend under the impulse of springs 25. The cups seize the top most sheet of the stack and lifts the sheet upwardly upon the reentry of air into cylinder 24.

With the rearward movement of carriage 16 the sheet is drawn by the suction cups 22 over constantly moving belt conveyor 27 and the sheet is then by valves 50 released by the cups to travel on conveyor 27. This conveyor is driven by motor 28. Initially the conveyor 27 is inclined downwardly, as indicated in dotted lines, so that the sheet has less of a drop into the collecting station upon secondary weighingscale 29 between guide plates 30 and 31.

One by one, additional sheets are picked off of stack by the suction cups 22 and placed on conveyor 27, by reciprocating carriage 16, to be deposited upon secondary scale 29. This action continues until the diminishing weight of the stack 5 reaches the preselected figure, when the reporting device 12 functions to stop movement of the carriage 16 and start conveyor 3 to discharge the stack now of the desired weight and to bring up a new overweight stack. Again reciprocation of carriage 16 and the pick-up action of suction cups 22 removes sheets from the new stack and delivers them successively to the secondary weighing scale 29* by conveyor 27.

Through the link 35 pivotally connected to wheel 36 conveyor 27 is slowly raised in accord with the growing height of the stack of sheets accumulating upon the secondary scale 29'. Motor 38 by which wheel 36 is revolved is operated in response to the number of reciprocations of carriage 16, whereby raising of the conveyor is synchronized with the number of sheets delivered to the secondary scale.

As additional stacks are brought to the selected weight by the removal of surplus sheets, the stack upon the secondary scale slowly rises until it also reaches the desired weight. At this point the reporting device 40 fixed before the dial 41 reacts to start motor 44, and therethrough conveyor 46, to move the completed stack 48 from the scale torward the baling station. The secondary scale 29 is now free to start collecting extra sheets to ultimately form another stack of standard weight. The response of reporting device 40 to the registration of the desired weight is communicated electronically to motor 38 to bring belt conveyor 27 back down to its original inclined position.

It may be observed that the use of the method and apparatus of the invention accomplishes the previously mentioned objects of producing bales of uniform weight.

The particular apparatus disclosed herein is for illustration only as it is realized that various other types of conveyors, controls and mechanical elements may be utilized in creating an apparatus embodying the features and spirit of this invention.

Accordingly, 'the appended claims should be interpreted sufliciently broadly to encompass any such obvious modifications or substitutions except where the language thereof is definitely specific to disclosed elements.

What we claim is:

1. A method of delivering stacks of sheets of wood pulp of a preselected weight from a stack forming station to a baling station comprising first forming a succession of stacks with each stack predeterminedly exceeding the preselected weight, conveying them in single file to a primary weighing scale, transferring excess sheets from each stack until the preselected weight is reached while the stack is on the primary weighing scale and stacking the excess sheets upon a secondary scale, and finally com veying the stacks reduced to the preselected weight from the primary scale and the stacks from the secondary scale as soon as they reach the preselected weight to the baling station.

2. A method of forming stacks of wood pulp sheets of a preselected weight and delivering them to a baling station which comprises establishing a first stack forming station in association with a wood pulp sheet producing apparatus, creating stacks at said first stack forming station consistently above the preselected weight, delivering the stacks in succession from the first stack forming station to a primary weighing scale, removing sheets one at a time from each stack arriving at the primary weighing scale until the weight of the stack is reduced to the preselected weight, delivering the removed sheets directly to a secondary scale constituting a second stack forming station, building up successive stacks of the preselected weight upon the secondary scale, and conveying the stacks as they reach the preselected weight from both the primary and secondary scales to a baling station.

3. A system of forming and transporting stacks of sheets of wood pulp froma sheet producing machine to a baling station comprising establishing a first conveyor line from the sheet producing machine to the baling station, creating stacks individually of a weight consistently above the preselected desired final weight of the stacks from sheets arriving fromthesheet producing machine, moving the created stacks successively along the said first conveyor line to a primary weighing scale, removing sheets one at a time from each stack arriving at the primary weighing scale until the weight of the stack is reduced to the preselected desired final weight, taking the sheets as they are removed and stacking them on a secondary scale, establishing a second conveyor line to the baling station from the secondary scale, and delivering the stacks as they reach the preselected desired final weight along the first and second conveyor lines from the primary and secondary scales to the baling station.

4. Apparatus for forming stacks of sheets of wood pulp of a preselected weight and conveying them to a baling station including stack forming apparatus, a primary scale, a conveyor for delivering stacks of weight above the preselected weight in sequence from the forming apparatus to the primary scale, a secondary scale, means removing sheets from each stack arriving upon the primary scale and building a new stack therewith upon the secondary scale, a baling station, actuating means associated with each scale and responsive to the registration thereby of the preselected weight and conveyor means mativated by said actuating means, carrying stacks of the preselected weight from both the primary and secondary scales to the baling station.

5. Apparatus according to claim 4 in which the means removing sheets from each stack arriving upon the primary scale and building a new stack therewith upon the secondary scale includes sheet lifting mechanism, suction cups as a part of such mechanism seizing successive sheets, a belt conveyor between the primary scale and the secondary scale receiving sheets released by the sheet lifting mechanism and depositing them upon the secondary scale, and means inclining the belt conveyor toward the secondary scale at a continuously slighter angle as each stack of sheets accumulated upon the secondary conveyor increases in height.

References Cited in the file of this patent UNITED STATES PATENTS 1,141,277 Smith June 1, 1915 1,711,100 Payzant Apr. 30, 1929 2,183,293 Leach Dec. 12, 1939 2,497,149 Berdis et a1. Feb. 14, 1950 2,834,388 Meyer 9-, May .13, 1958. 

